December 8, 2022

This video describes how Albuterol (Beta 2 agonists) cause bronchodilation by G protein coupled receptor mediated signaling.

In this video i’m going to talk about mode of action of beta-2 agonists so beta-2 agonists are actually bronchodilators good bronchodilators so these beta-2 agonist could be actually used in the treatment of asthma or other reversible pulmonary diseases so one good example of this be two agonists are albuterol it’s a prototype ik beta-2 agonist and in this video

I’m going to describe how this beta-2 agonist imparts its effect that means how bitter to agonist helps in bronchodilation so bronchodilation means are the relaxation of the smooth muscles of the bronchioles so how beta-2 agonist performs those and what are the exact signaling mechanism beneath this so here for instance that is assumed this dot represent of beta-2

Agonist such as alberto ron so this bill – agonist bind to its receptor that is a beta 2 receptor on the lung beta 2 receptor is found on lungs so these beta 2 receptor is our seven transmembrane domain protein it’s a g-protein coupled receptor also so when ligand that is the beta-2 agonist bind to this g-protein coupled receptor are the membrane bound g-protein

Undergoes a conformational change and the gdp with the alpha subunit is getting hydrolyzed and exchanged with a gtp now the alpha subunit bound with the gtp is active and this activated alpha subunit goes and it activates adenylate cyclase as we have seen in the basic mechanism of basic outline mechanism of any g-protein signaling cascade and then the second

Messenger cyclic amp ii would be generated from atp and so on so for the basic mechanism is the same so what is the physiological effect of this mechanism so these fish are these whole signaling pathway will impart to physiological effect one is it tivitz the myosin light-chain kinase this marched in light-chain kinase is actually important for muscle contraction

So if these myosin light-chain kinase or ml ck is inactivated then the muscle contraction could be prevented and decrease in intracellular calcium and in a moment we will see how these two effects are actually regulated so in normal cases calcium would form a complex with calmodulin and calmodulin will activate this ml c k that is the myosin light-chain kinase

And the myosin light-chain kinase will phosphorylate the myosin light-chain when myosin light-chain is phosphorylated it can form cross which with acting and the result would be muscle contraction now what happens the as a result of beta-2 agonist binding to the receptor it imports a signal which tells the cell to inactivate the myosin light-chain kinase so once

The myosin light-chain kinase is inactivated what happens this phosphorylated the myosin light-chain is not formed and these cross bridges are not from so muscle contraction cannot take place so thus beta-2 agonist mediated signaling preventing the muscle contraction and ultimately it imparts the effect of bronchodilation it also decreases the calcium 2 plus level

And indirectly are inhibiting the muscle contraction in this way beta-2 agonist such as albuterol imparts its effect are by causing bronchodilation hope you liked this video and you have enjoyed thanks light please and please subscribe

Transcribed from video
Mechanism of action of Beta 2 agonist By Animated biology With arpan